Increased serum thyroglobulin levels and negative imaging in thyroid cancer patients: are there sources of benign secretion? A speculative short review

The role of Tg kinetics in predicting 2-[18F]-FDG PET/CT results and overall survival in patients affected by differentiated thyroid carcinoma with detectable Tg and negative 131I-scan

PURPOSE

The aim of this study was to assess the potential role of thyroglobulin (Tg) kinetics in predicting 2-[¹⁸F]-FDG-PET/CT results and overall survival (OS) in patients affected by differentiated thyroid carcinoma (DTC) and suspected recurrence.

METHODS

On hundred and thirty-nine patients were retrospectively included. All patients underwent 2-[¹⁸F]-FDG-PET/CT due to detectable Tg levels and negative [¹³¹I] whole-body scan. The last two consecutive serum Tg measurements before PET/CT were used for Tg-doubling time (TgDT) and Tg-velocity (Tg-vel) calculation. Receiver operating characteristic (ROC) curves were used to determine the optimal cutoff points for Tg, TgDT and Tg-vel for predicting PET/CT results.

RESULTS

One hundred and fifteen (83%) patients had positive PET/CT for DTC recurrence, while the remaining 24 (17%) negative. Stimulated Tg before PET and Tg-vel were significantly higher in patients with a positive PET/CT scan than negative scan (average Tg 190 vs 14 ng/mL, p = 0.006; average Tg-vel 4.2 vs 1.7 ng/mL/y, p < 0.001). Instead, TgDT was significantly shorter in positive scan (average TgDT 1.4 vs 4.4 years, p < 0.001). ROC curve analysis revealed the best Tg, TgDT and Tg-vel cutoff of 18 ng/mL,1.36 years and 1.95 ng/mL/y. In patients with Tg<18 ng/mL, the PET/CT detection rate was significantly lower in patients with low Tg-vel (p = 0.018) and with long TgDT (p = 0.001). ATA class risk, PET/CT results and Tg before PET were confirmed to be independent prognostic variables for OS.

CONCLUSIONS

Tg kinetics may help to predict 2-[¹⁸F]-FDG-PET/CT results in DTC patients with negative [¹³¹I]WBS and detectable Tg, especially in case of low-moderate Tg.

Evaluation of a new automated assay for high-sensitivity thyroglobulin measurement and comparison with two established high-sensitivity thyroglobulin assays

Objective

Thyroglobulin (Tg) is an important tumor marker for therapy control and follow-up of differentiated thyroid carcinoma (DTC). Over the past decade, assays for highly sensitive Tg measurement have become increasingly established. We evaluated a newly developed high-sensitive Tg assay running on an automated platform (LIAISON® Tg II Gen assay, DiaSorin), with a limit of quantification of 0.10 ng/ml.

Design and Methods

Tg values of 166 sera from subjects without thyroid diseases and of more than 500 sera of well-defined DTC patients were determined with the new LIAISON® Tg II Gen assay and compared with two established assays (Elecsys® Tg II/Roche, and Medizym® Tg REM/Medipan).

Results

Tg reference values from healthy subjects were up to 37.93 ng/ml (women) resp. 24.59 ng/ml (men) with the LIAISON® Tg II Gen assay. Tg values showed good correlations in healthy subjects and patients with active tumorous disease. In contrast, Tg values in the very low range from cured thyroidectomized patients were poorly comparable between the three assays, while clinical differences between the cohorts were correctly reflected by all assays.

Conclusions

With the new LIAISON® Tg II Gen assay, another automated assay standardized against the first International Reference Preparation CRM-457 for highly sensitive measurement of Tg values is available.

Thyroglobulin doubling time offers a better threshold than thyroglobulin level for selecting optimal candidates to undergo localizing [18F]FDG PET/CT in non-iodine avid differentiated thyroid carcinoma

PURPOSE

To investigate the potential role of serum thyroglobulin doubling time (TgDT) in predicting 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) PET/CT results in patients affected by differentiated thyroid carcinoma (DTC) who demonstrated a combination of positive Tg but a negative [¹³¹I] whole-body scan ([¹³¹I]-WBS).

MATERIALS AND METHODS

Inclusion criteria were (1) prior [¹³¹I] treatment for DTC, (2) negative subsequent [¹³¹I]-WBS, (3) no interfering anti-Tg antibodies, (4) three consecutive Tg measurements under the thyroid hormone replacement therapy to calculate TgDT before 2-[¹⁸F]FDG PET/CT, and (5) at least 6 months of clinical and/or imaging follow-up to ascertain the diagnosis. Receiver operating characteristic (ROC) curve and the area under the curve (AUC) were used to identify the optimal cutoff point for the last stimulated Tg and TgDT prior to [¹⁸F]FDG PET/CT.

RESULTS

One hundred and thirteen patients were included. Seventy-four (65%) patients had positive [¹⁸F]FDG PET/CT for DTC recurrence, while the remaining 39 (35%) negative. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of [¹⁸F]FDG PET/CT were 92%, 94%, 97%, 87%, and 93%. Patients with positive [¹⁸F]FDG PET/CT had higher Tg and TgDT than those with negative PET/CT. ROC curve analysis revealed an optimal Tg cutoff of 19 ng/mL (sensitivity 78%, specificity 85%, AUC = 0.844) and TgDT of 2.5 years (sensitivity 93%, specificity 87%, AUC = 0.911). TgDT threshold of 2.5 years predicted significantly (p = 0.023) better than Tg level PET/CT results.

CONCLUSIONS

The diagnostic performance of [¹⁸F]FDG PET/CT could be significantly improved when TgDT is less than or equal to 2.5 years, as compared with using the absolute Tg level.

Hyperplastic thymus with increased angiogenesis is correlated with elevated serum thyroglobulin level in differentiated thyroid cancer patients with TENIS syndrome

Aims

To investigate the association between angiogenetic activity of hyperplastic thymus and serum thyroglobulin (Tg) level in differentiated thyroid carcinoma patients with thyroglobulin (Tg)-elevated Negative Iodine Scintigraphy (TENIS) Syndrome.

Methods

A cohort of 30 consecutive patients who underwent total thyroidectomy followed by radioiodine ablation and had TENIS syndrome received integrin α_vβ₃ targeted imaging with ^99mTc-HYNIC-PEG4-E[PEG4-c(RGDfk)]2 (^99mTc-3PRGD2). The correlation of angiogenetic activity of the thymus and the serum Tg levels was evaluated in patients with enlarged thymus.

Results

Enlarged thymus was detected in 9 out of the 30 TENIS patients and all hyperplastic thymus showed an increased accumulation of the tracer (median tumor/background ratio: 2.8). Five of them had only mediastinal uptake and surgical removal of the mediastinal mass in one provided histopathologic evidence of thymic tissue. The other four were not assigned further treatment and were free of disease in the follow-up, though their stimulated Tg levels consistently increased. Four out of the 9 patients showed ^99mTc-3PRGD2 uptake outside the mediastinum were assigned surgery followed by radioiodine treatment. Their stimulated Tg levels decreased after iodine ablation, but not drop back to normal. A significant linear correlation was observed between serum Tg levels and the degree of angiogenesis in the hyperplastic thymus.

Conclusions

The angiogenetic activity in hyperplastic thymus was related with the consistently elevated serum Tg levels in TENIS syndrome patients. Based on the existing literature and current data, we propose further intervention for patients with RGD uptake outside thymus, while close follow-up for patients with only mediastinal uptake.

Recurrence Incidence in Differentiated Thyroid Cancers and the Importance of Diagnostic Iodine-131 Scintigraphy in Clinical Follow-up

Objective:

Differentiated thyroid cancers (DTC) are tumors with good prognosis. However, local recurrence or distant metastasis can be observed. In our study, we aimed to investigate the incidence of recurrence and the importance of diagnostic iodine-131 whole body scan (WBS) in clinical follow-up in patients with DTC.

Methods:

The clinical data of 217 patients with DTC who were followed-up more than 3 years were reviewed retrospectively. The incidence of recurrence was investigated in a group of patients who had radioactive iodine (RAI) treatment and showed no sign of residual thyroid tissue or metastasis with diagnostic WBS that was performed at 6-12 months after therapy and had a thyroglobulin (Tg) level lower than 2 ng/dl.

Results:

At the time of diagnosis, ten cases had thyroid capsule invasion, 25 cases had extra-thyroid soft tissue invasion, 11 patients showed lymph node metastasis and four patients had distant organ metastasis. One hundred forty-five patients had RAI treatment at ablation dose (75-100 mCi), whereas 35 patients had RAI treatment at metastasis dose (150-200 mCi). Thirty-seven patients with papillary microcarcinoma did not receive RAI treatment. In 12 (%7.5) of the 160 patients who were considered as “successful ablation”, a recurrence was identified. Recurrence was detected by diagnostic WBS in all cases and stimulated Tg level was <2 ng/dL with the exception of the two cases who had distant metastasis.

Conclusion:

Identification of pathological findings with WBS in patients who developed local recurrence in the absence of elevated Tg highlights the importance of diagnostic WBS in clinical follow-up.

Accuracy of unstimulated Basal serum thyroglobulin levels in assessing the completeness of thyroidectomy

Background

Complete excision is important for proper surgical treatment of thyroid disorders. Functional thyroid tissue can be identified based on the level of serum thyroglobulin (Tg), which is produced only by the thyroid follicular cells, and nuclear scan.

Methods

Serum thyroid stimulating hormone (TSH), free thyroxin (FT4), basal (unstimulated) Tg and anti-Tg antibody (anti-Tg ab) were measured at the sixth postoperative month in 100 patients with benign thyroid disorders treated by total thyroidectomy. Thyroid nuclear scan was obtained to identify functional remnant of the thyroid gland. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the Tg levels in assessing thyroid remnant were calculated.

Results

Positive scan showed thyroid remnant in 23 patients, among whom 16 were Tg positive (true positive) and seven were Tg negative (< 0.5 ng/mL) (false negative). In these patients, the nuclear scan revealed pyramidal lobe remnants. In 77 patients with negative scan, the Tg levels were also negative (true negative), and the PPV, NPV, sensitivity, specificity and accuracy of the Tg levels were 100%, 92%, 70%, 100% and 93%, respectively.

Conclusions

The positive basal Tg (> 0.5 ng/mL) level accurately indicated the functional thyroid remnant after total thyroidectomy. The negative Tg (< 0.5 ng/mL) level supported complete excision of the thyroid gland. The surgical completeness of total thyroidectomy was accurately evaluated based on the serum Tg levels. Therefore, serum Tg levels should be measured in postoperative follow-up to determine the completeness of total thyroidectomy.

How to manage patients with differentiated thyroid cancer and a rising serum thyroglobulin level

Serum thyroglobulin (sTg) is the marker for monitoring persistence/recurrence of differentiated thyroid cancer, in patients without sTg antibodies. Patients with undetectable basal sTg or peak sTg <2 ng/mL are cured with low risk to recur. Newly detectable level of sTg indicates the recurrence. The significance of increasing sTg in patients treated with emithyroidectomy or total-thyroidectomy but not ablated with radioiodine is undefined. A doubling time <1 year may be a poor prognostic factor, but this is more relevant in cases with high levels of sTg. Because of its sensitivity, neck ultrasound should be performed at any visit, especially when an increased sTg is seen.

Detectable thyroglobulin with negative imaging in differentiated thyroid cancer patients

In the absence of autoantibodies against thyroglobulin (Tg), Tg measurement nowadays is the cornerstone of clinical management of differentiated thyroid cancer patients. DTC patients presenting with a positive Tg measurement without an anatomical correlate on anatomic imaging provide a management challenge to the attending physician.

Based on the literature we will provide an overview of the most important steps to undertake in such patients and their potential clinical consequences.

Serum oncofetal fibronectin (onfFN) mRNA in differentiated thyroid carcinoma (DTC): large overlap between disease-free and metastatic patients

AIM

This study assessed if onfFN mRNA in the peripheral blood of patients with DTC can identify individuals with metastatic disease.

METHODS

Comparison of onfFN mRNA was made among 3 groups: disease-free, lymph node metastasis, and distant metastasis using real-time RT-PCR on 5 ml blood samples from each DTC patient.

RESULTS

Fifty-one patients were included: 30 (59%) were disease-free; 7 (13.7%) had lymph node metastasis; and 14 (27.5%) had distant metastasis. OnfFN mRNA levels in the 3 groups were significantly different (P=0.001) but with a large overlap and the expression being highest in the disease-free group. Subgroup analysis of the metastatic groups did not show any effect of age, cell type, and serum TSH, Tg, and antiTg on onfFN mRNA. The within-run and between-run root mean square coefficients of variations were <2%.

CONCLUSION

OnfFN mRNA in patients with DTC cannot identify those with metastatic disease.

Is there a role for unstimulated thyroglobulin velocity in predicting recurrence in papillary thyroid carcinoma patients with detectable thyroglobulin after radioiodine ablation?

Background

In the follow-up of papillary thyroid cancer (PTC) patients treated with curative thyroidectomy and radioiodine ablation, raised thyroglobulin (Tg) predicts recurrence with reasonable sensitivity and specificity. However, a proportion of patients present with raised Tg level but no other clinical evidence of disease. Only limited data on Tg kinetics have been reported to date. Here we aim to evaluate the prognostic and predictive significance of nonstimulated serum Tg velocity (TgV).

Methods

Consecutive PTC patients treated with curative thyroidectomy and radioiodine ablation between 2003 and 2010 were analyzed. Patients with at least one detectable Tg measurement (>0.2 ng/mL) were included. TgV was defined as the annualized rate of Tg change. Logistic regression analyses were performed to evaluate the role of TgV in the prediction of disease recurrence. The optimal TgV cutoff was assigned by receiver–operating characteristic curve analysis. Overall survival of patients above versus below the TgV cutoff were determined by the Kaplan–Meier method and compared.

Results

Of a total of 501 patients, 87 had at least one Tg value >0.2 ng/mL; in these latter patients, 29 (33.3 %) developed recurrence. TgV was an independent predictor of the recurrence. TgV ≥0.3 ng/mL per year predicted recurrence with a sensitivity of 83.3 % and specificity of 94.4 %. Patients with TgV below the cutoff had a significantly better overall survival (p = 0.038).

Conclusions

TgV predicts recurrence with high sensitivity and specificity, and is a prognosticator of survival in postthyroidectomy and postablation PTC patients with raised Tg.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-012-2391-6) contains supplementary material, which is available to authorized users.